Satellite Communications/HPA backoff
Dear sir , Can you tell me about HPA backoff ?
Sorry for the delay, I was on a business trip.
An amplifier works optimal in the linear range where minimal distortion is created on the signal. However, we try to operate the HPA at the highest output power. When approaching this maximum output power, distortion is created. This is because the HPA starts to operate in the non-linear region.
In order to avoid excessive distortion, it is advised to operate the HPA at a certain amount of dBs away from the maximum (saturation) output power. This amount is called the HPA back-off.
For example if an HPA has a saturated output of 400 W and a running a 16APSK signal, typically an HPA output backoff of 3 dB is advised, so the HPA can be operated at a maximum output power of 200 W.
I hope this answers your question,
Best regards, Dave